PURPOSE: To prevent overcooling or overwarming by a method wherein, when the number of revolutions of an indoor-side blower has increased above a second prescribed number of revolutions which is larger than a first prescribed number of revolutions, the control of the compressor and the indoor-side blower, until the supplied-air temperature is brought back to the previous prescribed point, is shifted to a transitory step that the capacity of the compressor is fixed on the one hand and the number of revolutions of the indoorside blower is gradually decreased on the other hand.

CONSTITUTION: In the operation of an air conditioner, when, while the control keeps the supplied-air temperature constant, the number of revolutions of an indoor-side blower 3' has decreased below a first prescribed number of revolutions, the prescribed supplied-air temperature is, in the case of cooling, elevated by a specific value and, in the case of heating, lowered by a specific value. When subsequently the number of revolutions has increased above a second prescribed number of revolutions which is greater than the first prescribed number of revolutions, the control of the compressor 6 and the indoor-side blower 3', until the supplied-air temperature is brought back to the previous point, is shifted to a transitory step that on the one hand the capacity of the compressor is fixed, suspending the control of keeping the supplied-air temperature constant, and on the other hand the number of revolutions of the indoor-side blower is gradually decreased. As a result, when the prescribed temperature is brought back from the point for a low air-conditioning load to the point for an ordinary load, there is no possibility of the air-conditioning capacity increasing out of proportion to the air-conditioning load, hence no overcooling in cooling or no overwarming in heating.